Polymers that contain conjugated structures in their molecular structures (hereby denoted as conjugated polymers) have enthused considerable interests owing to their unique optoelectronic properties, low cost, and ease of processing that promise an important role in future lighting, photovoltaics, and microelectronics. With the π-orbitals extending along the backbone in the conjugated polymers, they harvest photons to generate electron-hole pairs (also denoted as excitons in some cases) that are known to interact strongly with the vibrations of polymer chains (electron-phonon interactions) to result self-trapping and retarded charge recombination. The driving force of the electron-phonon interactions may be linked to the elevated local Coulomb energies introduced amid the excited states and the surrounding backgrounds. In abating the energy increase, the excited states, extending across several monomer units, may interact with chain vibrations to accumulate local molecular deformations. The local molecular deformations introduced because of the excited states will trap and immobilize the excited states and form the so-called self-trapping effect, such that the excited states cannot perform phase-coherent in-chain migration and only can implement hopping movement or release energy through non-radiative pathways at the self-trapping point to return the original low-energy state from the excited states. Generally, the non-radiative pathways may dissipate up to well above 90% of the total absorbed energy. Low quantum yields have long been the major hurdle for the industries to develop and mass produce viable polymer devices.
Accordingly, there is still a need for a solution to solve the aforementioned problems.